By Stacie Martin
Why do plants need water? Plants are made up of 90% water and use it for many different plant processes including food creation through photosynthesis, carbon dioxide exchange, cooling through transpiration, and meeting the cells requirement for plant structure.
Plants that are newly planted or have sustained construction damage require more water than established plants. This is because their root systems are smaller. Watering at Gathering Place is one of the most essential activities to establish the new plants.
Plants prefer rainwater, as it has higher levels of oxygen and nutrients. In the hotter months, Oklahoma has less rainfall so our horticulture team supplements with irrigation. As Gathering Place’s plants develop established root systems, they will require less water and less irrigation. We are excited for that day!
There are a few ways we check to see if irrigation is needed. Providing too much extra water to the plants is just as detrimental as providing too little. Plants need an average of 1-2” of water a week. If we notice it has not been raining, we do a visual inspection around the Park. One thing we look at is leaf turgidity, which is the pressure of the cell contents that holds the shape of the plant. When the turgidity levels are low, the plant will start to wilt. This is what is happening with this buckeye pictured below.
Another thing we check is soil moisture. We check the soil with a soil probe, which pulls a sample that we can inspect. After rainfall or irrigation, we like to see the depth of the soil moist for approximately one foot. Typically, if the soil probe enters the ground relatively easily and the soil clumps together there is enough moisture. Different plants like different amounts of water, so it is good to make note of the various species as well.
Gathering Place has a large irrigation system. This is great because it helps our horticulture team minimize hand watering and maximize watering efficiency. Our irrigation program is computerized, allowing us to make necessary adjustments. We have both irrigation heads, like on the QuikTrip Great Lawn and in the prairie grass areas, and drip tube in the shrub beds and around the tree rings. Gathering Place has over 77 miles of drip tube! Utilizing an irrigation system helps us to soak the ground to a deeper level because we can set the system in intervals that slowly let the water percolate down. The roots follow the water, and the deeper the roots grow, the more drought-tolerant the plant is.
Since our irrigation system is so vast, we encounter a lot of irrigation repairs. Some issues are caused by squirrels chewing holes in the drip tube, some are caused by rocks clogging the system, and others are breaks caused by pressure, shovels or stakes. It is important to keep any irrigation system fully pressurized.
Sometimes the opposite is true! Plants do not just need water, they also need air! We add drainage to areas that tend to have standing water after Oklahoma rainstorms..